U.S. health officials announced on Friday the recall of some liver sausage and canned meat products from Boar's Head as part of their investigation into a listeria outbreak that has sickened nearly thirty people and resulted in two deaths.

The U.S. Department of Agriculture said Boar's Head Provisions Co. recalled liver sausage because it may be contaminated with listeria bacteria. The agency stated that a sample of Boar's Head liver sausage from a store in Maryland tested positive for listeria.

The USDA also stated that the company is recalling deli meats that were manufactured on the same day on the same line as the contaminated liver sausage at a Virginia facility. The sample was from an unopened package collected by health officials as part of the investigation into the listeria outbreak.

Health officials said tests are ongoing to determine whether the liver sausage sample is linked to the outbreak.

The Sarasota, Florida-based company said in a statement: "We are fully cooperating with government authorities and conducting our own investigation into this incident."

The listeria outbreak was first reported last week. Since late May, 34 people have fallen ill across 13 states, with all but one being hospitalized. Two people have died - in Illinois and New Jersey. Officials said it could take weeks for symptoms to appear, so there may be more cases.

Officials noted that people who reported eating sliced turkey, sausage, and ham were often included.

Listeria can contaminate food and make those who consume it ill. Symptoms include fever, muscle aches, nausea, and diarrhea. It can be treated with antibiotics, but it is particularly dangerous for pregnant women, newborns, the elderly, and those with weakened immune systems.

According to the Centers for Disease Control and Prevention, it is estimated that 1,600 people get listeria food poisoning each year and about 260 die from it.

Boar's Head's recall of more than 200,000 pounds shipped nationwide applies to deli meats at the cold cut counter, not pre-packaged meats. It includes a number of multi-pound packages stamped with a sell-by date of August 10, including bologna, garlic bologna, beef bologna, beef salami, Italian-style capicola, and spicy capicola. It also includes bacon wrapped in steak, which has a sell-by date of August 15.

The company advised customers to discard the recalled products or return them to the store for a refund. Health officials said refrigerators should be thoroughly cleaned to prevent cross-contamination of other foods.